The present invention relates to burners for gaseous fuel and particularly burners of the type employed for cooking appliances such as cooktop arrangements where a plurality of burners are disposed on top of a cabinet for cooking food in receptacles. The invention relates particularly to household cooktop burners where a plurality of burners are supplied from a manifold connected to a source of fuel gas with individual user operated control valves for regulating the flow of gaseous fuel to the individual burners.
Heretofore, it has been commonplace to have a plurality of top burners on a domestic gas range arranged in an array with the individual burners having an annular or generally ring-shaped configuration with the flame generating ports disposed in peripherally spaced relationship to provide a ring of discrete flames emanating from the burner ports. It is known to provide such a burner with a base having a tubular inlet portion and an enlarged diameter end flange for defining a plenum or air/fuel mixing cavity which is closed by a burner cap. The flame-generating ports in such a known burner design are formed in the outer annular rim of the base cavity, such that when the cap is in place gaseous fuel flowing into the tubular inlet is mixed with air typically by an inlet aspirator and is discharged through the burner ports for flame generation. Such known burners employing a base and cap have formed the flame-generating ports extending radially through the outer rim of the base which are closed by the cap to form flame-generating ports.
In such an aforesaid cooktop burner arrangement, when rapid fluctuations in the flow velocity of fuel due, for example, to variations in the fuel supply pressure occur, a condition known as "blowing" occurs where the flame is separated from the flame generating port. Variations in the fuel/air mixture ratio can also produce flame separation; and, such conditions are experienced upon ignition of flame on a cold burner. Flame separation has also been experienced when the burner supply line is preheated from the proximity to a hot oven located below the top burner. In such an arrangement, a condition referred to as a "hot-hot" condition can occur, where the presence of a hot oven superheats the fuel in the top burner supply tube and burner plenum causing increased flow velocity in the flame generating ports, resulting in flame separation. Thus it has been desired to provide a cooktop gaseous fuel burner which has a stable flame at varying fuel flow rates and varying ambient conditions and to provide such a burner at low cost in high volume mass production.